sync with head.
for a reference, the tree before this commit was tagged
as yamt-pagecache-tag8.
this commit was splitted into small chunks to avoid
a limitation of cvs. ("Protocol error: too many arguments")

- If the stdout is not a tty, prevent formatting unless forced with -i
- Don't ever page unless asked for with -p
- Introduce "legacy mode" (-l)
1. searches only name and name_desc, prints name(section) - name_description
2. turns off escape formatting (can be forced on with -i)
3. turns off context printing (can be forced on with -c)
- Parse the environment $APROPOS variable as an argument vector.
With these changes one can simply 'export APROPOS=-l' and get the old apropos
behavior.

- move the terminal handling in apropos-utils.c since htmp and pager are also
handled there.
- underline the name, section, and description so that it is prettier.
- change to bold terminal the terminal highlighting to match with less

Make mandb path configurable. makemandb (and related tools) use
the path from the _mandb variable from man.conf now.
Set _mandb in man.conf to same value as was used before.
From Abhinav Upadhyay <er.abhinav.upadhyay@gmail.com>.

Import the new apropos/whatis.
This code has been developed by Abhinav Upadhyay as part of Google's Summer
of Code 2011. It uses libmandoc to parse man pages and builds a Full
Text Index in a SQLite database. The combination of indexing the full
manual page, filtering out stop words and ranking individual matches
based on the section gives a much improved user experience.
The old makewhatis and friends are kept under MKMAKEMANDB=no for now.